birth_year = input('Birth year: ')
print(type(birth_year))  # 输出为<class 'str'>
age = 2021 - int(birth_year)  # 输出为<class 'int'>
print(type(age))  # 输出为<class 'int'>
print(type(True))  # 输出为<class 'bool'>
print(age)  # 输出为年龄27
